From B.c. Seven Century to B.c. Three Century that is called the Spring and Autumn Period and the Warring States Period, The princes of many little states began to fight and swallow up each other. They all built the long city wall for self-defence.
B.c. 221 Year, QinShiHuang consolidated all six states, He pulled down the wall between the states one side, the other side he built the new city wall in the north to defense the Hun. He command MengTian general and thousands upon thousands people to build the new city wall, it stretch more than five thousand kilometre in an unbroken chain, which is the oldest Great Wall